Document their timeline, versus the timeline you made and continue to make your updates.
Is there a feature you could add? Like muting the sped up ads? If you can demonstrate an "echo" of features, that'll go a long ways to proving your position.
But can you do anything about it? Not really, unless you hire a lawyer in their jurisdiction.
I had this problem back in Y2K when someone was stealing my work and not attributing it to me. They even stole the history portion, and simply cut/replaced with their name, using the exact same wording. But all I could do was annoy the hell out of them until they stopped. I actually found the customer they were dealing it off to, and informed them, using the wayback machine to prove that everything in their docs was actually my material. That finally put an end to their shenanigans.